With the developments of industry and commerce, a large number of people migrate into the cities thereby increasing the population density of the metropolis. For solving the problem of crowded living space, tall buildings and great mansions are built to take the place of traditional solitude house to provide people adequate living space. Under this condition, various apartments, dwelling, and multi-storey buildings are built and become the first choice when the common people want to buy a house.
However, for the great part of community dwellings, the traffic thoroughfares in the peripheral circumstances extend to all directions, thereby making the community open to public access. Under the condition of less private matters, it is easy for thieves and bandits to make an incursion that causes the security safeguard more difficult. Especially, when the political and economical affairs fluctuate considerably, the legal cases, such as steal, robbery and even arson, are continuously rising and render the public security corrupting. Further, because the resident families usually do not know each other in the multi-storey buildings, the identities of persons entering the building can not be recognized and controlled effectively, thereby lowering the security.
Besides, for current multi-storey buildings, they have a great deal of resident families, so it is difficult to fabricate an intercom on the front gate of the community, comprising the large number of buttons responsive to the doorbell of each resident family, to allow the visitors can contact with some residents directly. For solving this issue, in the large community or building, they usually establish a community managing commission for monitoring the entrance of the building to reduce the hazards of lawless invasions. The typical manner is to set up a guardroom adjacent to the front gate of the community or building, to examine and recognize all the persons want to enter. And for further prohibiting from the disturbing by non-residents, some ID recognizing means or entrance guard means can be fabricated on the gate to recognize the identities of people entering the building.
It is noted that the above manner still encounters some problems. First, the security guards usually spend lot of labor effort on some sundry duties and thereby unable to pay attention to the security protection of the community. For example, to lock/unlock the gate is controlled by the security guards, that means when visitors want to visit some one resident, the security guard have to contact with the resident via the intercom and ascertain the identity of the visitor, and then to open the gate for entry. Once a lot of persons want to enter in or go out, the security guards have to face lot of asking and will be too busy to make proper entrance management.
Further, when the resident is not at home or is not available to answer the intercom, the security guard should be incapable of ascertaining the visitor's identity. Though in some community or building, the residents will be requested to provide the urgent phone numbers for emergent contact. However, this manner will increase the hazards of revealing private matters of the residents, especially when the members of the community managing commission leave their jobs. So how to keep the private matters of the residents and how to provide more effective entrance guarding have become the important issues nowadays.